Conventional dispensing systems for liquids generally comprise a pressurized supply and a dispensing valve which is open for a predetermined period of time such that a predetermined quantity of liquid is delivered therethrough. While systems of this type are suitable for many purposes, they are not entirely suitable for viscous substance such as syrup, custards, jellies or materials which contain semi-solid elements. The quantity of substance which may flow in a given time may vary, and shut off of the dispensing valve may be difficult.
In prior U.S. Pat. Nos. 3,734,352 and 4,006,847 by Dooley, dispensing systems are disclosed and claimed including a pilot operated spool valve for controlling the dispensing cylinder in one case, and manually operated spool valve for controlling a differential pressure operated dispensing cylinder in the other case. These systems are effective in solving the problems associated with viscous substances in that positive displacement of a definite quantity of material is provided together with quick severing of semi-solid elements in the dispensed material through action of the spool valve.
The present invention comprises additional improvements in this general type of apparatus wherein the entire apparatus is simplified from the standpoints of design, manufacture and installation.